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Antioxidants

Hi Guys,

By now I have clocked up over 65,000+kms on WVO without any recent issues.

I had only one major issue during my early WVO days: my IP was playing up, but it turned out that it was just some oxidized oil blocking my inlet strainer to the IP. Of course, I was told that I "have to do" a complete IP reconditioning (This was at AG Diesel, in Springvale, do not ever go there!). I won't say more, it has been fully documented here:

I wanted to start this thread for ages, but never got to it. Recently, I helped someone with a conversion and it reminded me to start this thread as a way of giving back some important lessons I have learnt on this journey.

After I had the issue with my IP, I wanted to really understand what went on and below is what I came up with:

One important aspect of running on WVO that is not often addressed here is oxidization.

I am sure, most people here are familiar with oxidization, but for the benefit of those that are not, let me write a few words. In brief, oxygen getting into oil will react with the oil molecules and bond to them, connecting 2 molecules together. The result is that you end up with a longer molecule, which in turn can get even longer through further oxidization. Eventually you end up with a sticky gum, as these long molecules are unable to flow anymore and stick together. Really your oil is pretty much turning into plastic.

This gum in my view is second most important problem after filtering (even water is less of an issue IMHO - with sensible precautions of course).

The way to avoid oxidization is:

1. Store oil with as little oxygen as possible. If you plan to store it in a drum for a longer period, then put the drum as full as possible and screw and tighten the top. This way no new oxygen can enter and also there is little oxygen in the container, which once "used up" will not provide further damage. You will need to leave a little space if you fill your container in winter as it will expand during summer months and escape the container!

2. Store your oil in plastic containers. All my large drums are made of plastic. Metal can be a catalyst to oxidization, so best to stay away from it.

3. Use antioxidants. If you check cooking SVO, it always has antioxidants in it. However, WVO has most of it gone, so it is not going to like being stored for a long time. This is the hardest part and I will address it further down.

4. Avoid using additives that encourage oxidization. I always put a diesel additive in my 100&#37; WVO that I am running on, to kill any forming bacteria and help the engine a bit. But make sure that these additives are not going to ruin your fuel (as it is designed for diesel and not WVO).

To address antioxidants a bit more, the major issue is that they are not easily available in this country. I tried to source multiple types, and found that it is mostly available in large quantities only. I then talked to additive makers to try to get them interested to repackage and sell them in smaller quantities. Not much luck so far, even though one mob was interested and I supplied them with studies etc (I have no commercial interest in it, my field is elsewhere).

However, I have managed to obtain samples and have been using them for quite some time. I have been stretching them as far as possible, so they would last longer. Since you only need like 3 teaspoonfuls in 20 litres, it does last a long time.

I was planning to run an experiment where I put a small amount of oil into 2 containers, one with antioxidant in it and leave it out in the sun during the hot summer months to see how they compare (I ended up missing that opportunity last summer). Well, maybe this summer...

Long story short, since my IP saga I have been using antioxidants, and I never have any problems (apart from occasional filter blocking)... actually correction, I did have one (similar) issue, but I am not going to stretch this article any longer, will leave that to next time...

Re: Antioxidants

Hi Surfie,
Thanks for an interesting and very readable post.
Your recommendations pretty much sum up my experience in handling WVO over the past five or six years.
The only point I'm not so sure about is the need to add an antioxidant. My bulk storage has been in plastic 1000lt IBCs.

These have been about half full most of the time and my fine filtered WVO IBC has never been emptied. In other words there must theoretically be oil still there which is up to five years old or so and so if oxidisation had commenced at any time it should spread to any oil in there. I do ensure that there is no free flowing air into the IBC and keep it as well sealed as I can. this IBC also sits next to a corrugated steel North facing shed wall and so gets quite a bit of heating in the warmer months.

Where I believe oxidised or polymerised WVO is an issue is where it commonly is exposed to both air and ferrous metal and that is just inside the filler pipe. I occasionally try to wipe the brown gum off my fuel cap thread and the opening into the fuel tank. Fairly certain that the crud caught in the MB prefilter that I have just prior to the lift pump and hence upstream of the OEM filter, CAV and IP emanates from the filler.

Re: Antioxidants

There are two headings in the FAQ at the top of the forum that refer to oxidation, but it's worth having a sticky of it's own, no pun intended, to make it easier for people who don't read the FAQ.

Once we have enough useful information in the sticky, we might close it off, or clean up the threads so it stays right on topic, so don't stress if that happens.

There have also been several postings about oxidation, often by me, where I rattled off a list of what causes this stuff. Off the top of my head they are anything that promotes a chemical reaction:

Heat
Oxygen - Air - Splashing around inside half full fuel tanks.
Plain steel fuel tanks are renowned for aiding oxidation. See the FAQ. This is not the case for factory fuel tanks, only aftermarket.
Water/moisture doesn't help much either.

I agree with Surfie's comments too.

By the way, guys who use lard don't have this problem, because lard is a more stable product than veggie oil. Sure it's harder to manage outside the vehicle, but in a well set up vehicle, lard has several advantages over veggie oil.

Draining your fuel tanks annually never does any harm, more often if you live in warm tropical conditions.
Neither does running a few tanks of straight biodiesel now and again.
ULP, unleaded petrol, changes the iodine value in the WVO and improves it's stability. No more than 15 percent ULP. Perhaps 1 to 5 percent would improve oxidation prevention - more info needed on that assumption.

Re: Antioxidants

Thanks Guys, very interesting thoughts...

I must say, though, that you both contribute to my initial point that using antioxidants is a good idea. Going by Laurie's comments, storage may not be a huge issue if done well. And I must say, I have never fully emptied my plastic drums either. Have not even taken stuff out the bottom for at least 1.5 years...

However, I do store dirty oil that I bring home in 20l veg oil drums and sometimes you can smell oxidization (especially in nearly empty drums - the ones waiting to be refilled). However, when I put antioxidants in it, the whole thing gets a nice sweet smell and stays like that for ages. I have been saving on antioxidants and recently only put it in more smelly drums. When I open them later however, I can almost tell which one had antioxidants in it, from the nice sweet smell. As a side note, slowly I am switching over to plastic containers.

Secondly, as both of you confirm, there are oxidization problems somewhere along the line, no matter how much care we take. Hence, my point:
Use antioxidants early in the process and it just won't go bad that easily later. Draining tanks, cleaning fuel fillers is too hard, buying petrol is too expensive, even at 10% :-) Just use some antioxidant and forget your worries!

Now, I am the first to admit that I do get some sticky stuff around the place where pipes seep (I use plastic garden irrigation pipes for the same reason, but they do not seal perfectly) or where oil is left to dry. However, I did not use the recommended dosage for antioxidants either. I was also planning to mix in some metal deactivators as well, so, it will stop/slow the reaction in the tank/pipes, but I never got my hands on any.

So, what I recommend is to use antioxidants (and if possible metal deactivators) with the correct dosage early in the process and do not worry about where the oil can go wrong. The antioxidant will last more then enough time in your car before the oil gets used. And it will help in storage/transfer etc.

Surfie
(PS. Tim - I did search the threads for antioxidants, perhaps I should have searched for oxidization)

Re: Antioxidants

after filtering I store my WVO in an overhead 1,000 ltr steel tank [plastic would be better] every couple of months I put a good squirt of lpg from my BBQ bottle into the tank. LPG is heavier than air so hopefully it sits as a blanket on top of the oil stopping oxidation

Re: Antioxidants

Maybe we can use some less flammable heavy gas like CO2? Not sure where to source it from though... Maybe the power companies would be happy to give you some free of charge. lol

On another note, antioxidants help you all along the process, ie even in your fuel tank etc. I can see that there is kind of a reluctance to use it from most of you, I wonder if it is a question of availability or cost or not seeing it as a problem?

Re: Antioxidants

CO2 you can get from your welding gas supplier it is used for migs also argon used in tigs both heavier than air and antioxidants I used to buy it years ago for welding but cant remember the price and i can get it free from work now, there are blends which you wont want.